This invention relates to a valve means which includes multiple valve members each having a first valve seat upon which the valve members are normally seated to insure positive shut-off of flow in a first direction through the assembly and wherein one of the valve members has a second seat against which the other valve member seats to prevent reverse flow through the assembly.
More particularly, the present invention relates to a dual valve assembly for use in intravenous administration sets to control flow therethrough in instances wherein more than one fluid is to be administered to a patient, as by means of multiple sources of fluids connected with a Y-connector or the like supplying the fluids to a common needle or cannula. In such arrangements, provision normally is made for interrupting flow from one of the sources while flow occurs from the other of the sources. Prior art arrangements for effecting this flow control usually involve various clamps and valve assemblies which must be manually operated in order to obtain the proper and necessary flow control. This, of course, requires the attention of a nurse or other attendant who must be present when one of the fluid sources is depleted so that the attendant can manipulate the valves to begin supplying fluid from the other source and thus prevent introduction of air into the vein of the patient.
Examples of some prior art arrangements are shown in U.S. Pat. No. 3,886,937 and in applicant's prior co-pending application Ser. No. 703,907.
In the present invention, the valve assembly is constructed of a minumum number of parts assembled together to provide a valve housing defining a first valve seat therein and having a first valve member reciprocable toward and away from the first valve seat. The first valve member is normally seated under the action of gravity and is moved to open position by an electromagnet positioned exteriorly of the housing. A valve stop member is spaced a predetermined distance from the seat to limit opening movement of the valve and a second valve member is mounted in the housing spaced upstream from the first valve member and is normally seated on a second valve seat under the action of gravity and of fluid pressure thereabove for preventing forward flow through the assembly. When the first valve member is opened by energization of the electromagnet, an elongate valve actuating rod is engaged by the first valve member and moved upwardly into engagement with the second valve member to open the second valve member and thus permit flow in a forward direction through the assembly. In the event of reverse flow through the valve assembly, as might occur, for example, when more than one fluid source is connected to a length of tubing, the second valve member moves upwardly against a second valve seat therefor to prevent reverse flow beyond the valve assembly.
The double seating action obtained by the use of multiple valve members to prevent or control flow in a first direction insures positive shut-off of flow and significantly reduces or even eliminates the problem of leakage of fluid past the valve members, as might occur if a single valve member is used, as in prior art constructions, and particulate material becomes trapped between the single valve member and its seat or the valve member itself is imperfect. Additionally, the unique structure of the dual valve assembly of the invention provides a means for preventing reverse flow through the valve assembly without requiring expensive and power consuming multiple valve control members. Also, the unique dual valve assembly of the invention is completely automatic in operation and does not require the presence of an attendant or the like to manipulate valves in order to prevent backflow of fluid through the system when multiple fluid sources are used, or to switch from one fluid source to another, as is necessary in prior art devices.